Cat colour calculator

Yes — completely free with no sign-up. Pick the sire and dam colours to see the kittens' colours and odds, or upload the pedigree so we can read the grandparents and hidden genes.

Some genes are recessive and stay hidden — like blue, chocolate, longhair and colourpoint. A cat can carry them without showing them, and if both parents carry one it can appear in the kittens. The calculator lists these under “Could also appear”, with the condition for each.

A male can't be tortie — red is carried on the X chromosome and a male has only one X. Tortie males are rare and usually sterile.

It is a danger to the kittens' lives — when the dam is type B and the sire type A, a kitten that is type A or AB has its blood destroyed by its mother's milk and usually dies within the first three days. The fix is known and proven: keep the kittens off the dam for the first 24–48 hours and feed them substitute milk or a foster mother, then return them. Don't start this mating unless you're ready for those two nights.